1. Field of the Invention
The invention relates to a device for controlling an automatic transmission of a motor vehicle. In conventional transmission control systems--for example for automatic transmissions, automated manual shift transmissions, stepless or CVT transmissions--the gear or the gear ratio is automatically selected and set as a function of defined input variables, as for example the gas pedal position and the vehicle speed.
Recently, the driver has to an increasing extent been given the option to influence the gear decision of the control device manually by means of a selector device. This may take place, for example, by means of displacing a selector lever, which is usually arranged on the central console of the motor vehicle, into a "manual" shift gate provided specially for this purpose and is arranged in parallel with the usual selector lever gate for automatic transmissions having the positions "P-R-N-D".
By displacing the selector lever into this additional manual shift gate, the driver leaves the automatic mode of the transmission control system, that is to say the automatic selection of the gear or ratio, in order to set the desired gear in a so-called manual mode of the transmission control system. Thus, by means of pushing the selector lever forward, in each case an upward shift is carried out, and by pushing the selector lever backward, a downward shift is carried out. This intervention option is intended to improve the acceptance of the automatic transmission by drivers who are used to manual transmissions. If the driver wishes to use the automatic mode of the vehicle again, he has to leave the additional shift gate, that is to say he has to displace the selector lever into the "P-R-N-D" shift gate (cf. German Patent DE 43 32 265 C1). An additional central shift gate of that prior art arrangement simply replaces the selector lever positions for the driving stages D1, D2 and so on of conventional automatic transmission control systems, in which a step by step limitation of the shifting by one gear in each case is predefined by the driver.
A disadvantage is that the driver is forced to make a definite decision for one of the driving modes. A change between the automatic mode and the manual mode must thereby be effected deliberately by the driver--by displacing the selector lever. In addition, the manual gate, that is to say the purely manual control of the transmission in the manual gate, has the particular disadvantage that a learning process for matching the adaptive transmission control system to the driver's inputs is not possible. Such learning processes presuppose that, in the automatic mode, the driver can also intervene manually, which defines the "ideal shifting behavior" to modify the adaptive transmission control system. For this purpose, the automatic mode and the option for manual intervention must so to speak be provided simultaneously.
An automatically shifting transmission (cf. German Published, Non-Prosecuted Patent Application DE 43 11 886 A1) has a driving stage lever for an automatic mode of operation and a rocker for a manually actuated mode of operation. The transmission control system changes from the automatic mode into the manual or driver-actuated mode of operation if the driving stage lever is moved into a position M or if the rocker is used to output a shift signal of a predefined duration. The driver-actuated mode of operation is terminated if the driving stage lever is moved into the M position again, or if an upward shift signal of a predefined duration is provided. The driver actuated mode may also be terminated after having been active for predefined time period.
A selector device for an automatic transmission (cf. U.S. Pat. No. 5,509,322) has a longitudinal gate for a selector lever for the automatic mode and, at one end of this longitudinal gate, two lateral lever positions for manually shifting up or down by one gear. An automatic return into the automatic mode is not provided.
Another selector device for an automatic transmission (cf. European Patent Disclosure EP 0 467 773 A1) contains a longitudinal gate for a selector lever for the automatic mode and a transverse gate for manually shifting up or down by one gear, the transverse gate is arranged at a position M located between the positions "D" and "1" of the longitudinal gate. A manual shift command is not executed if it would result in a stalling or over-revving of the engine.
In the case of a further shifting device for an automatic transmission (cf. European Patent Disclosure EP 0 685 664 A2), a selector lever can be pivoted in a first shift gate for an automatic mode, this gate being connected via a transverse gate to an H-shaped shift control pattern for a manual mode. At the point of intersection of the shift gate with the shift control pattern, a further shifting program is activated. This shifting program can be activated both, with the selector lever coming from the shift gate and from the shift control pattern. A manual shift signal is executed only if the target gear lies in the permissible range of engine speed.